Yan Ruoqu 閻若璩 (1636-1704), courtesy name Yan Baishi 閻百詩, style Qianqiu 潛邱, was an early Qing period 清 (1644-1911) philosopher. His family came from Taiyuan 太原, Shanxi, but later moved to Huai'an 淮安, Jiangsu. His biographers say that he was often sick in his youth and had to study very hard to master the traditionally venerated texts of the canon of Confucian Classics. For his motivation he sticked a placard to the door pillar, adhorting him to feel ashamed for everything he did not know, and to strive to obtain a little information from whomever he met. In the end he proved to be an excellent researcher, commentator and collator of the texs of the Classics. His hard studies had helped him to develop a stringent will to solve all inherent questions. Only in his later years he traveled to Beijing, where he attracted the attention of the Kangxi Emperor 康熙 (r. 1661-1722). After his death the emperor personally wrote the sacrificial text (jiwen 祭文) to his enterment.
The most detailed studies of Yan Ruoqu were made to the old-text version of the Shangshu "Book of Documents", Guwen Shangshu 古文尚書. This textual tradition had been neglected in the scholarly world since the end of the Jin period 晉 (265-420), and a related text, namely Du Yu's 杜預 commentaries to the Zuozhuan 左傳, were lost. During the Eastern Jin 東晉 (317-420) the scholar Mei Ze 梅賾 submitted a text that he called Guwen Shangshu, along with a forged commentary to it, called Shangshu Kongzhi zhuan 尚書孔氏傳. The old-text Shangshu was elevated as an official textbook in the National University (taixue 太學), side by side with the new-text Jinwen Shangshu 今文尚書 (see old-text and new-text debate). The Tang period 唐 (618-907) masters Lu Deming 陸德明 and Kong Yingda 孔穎達 served themselves drom these two traditions, but only an ill-arranged 29-chapters version (a new-text version) by Master Fu Sheng 伏勝 survived the Tang period. This version was believed to be a forgery, as Wu Yu 吳棫 and Zhu Xi 朱熹 argued during the Song period 宋 (960-1279). Discussions about the authenticity of Fu Sheng's version were produced by Wu Cheng 吳澄 during the Yuan period 元 (1279-1368) and Mei Zhuo 梅鷟 and Hao Jing 郝敬 during the Ming period 明 (1368-1644), and also by the early Qing philosophers Huang Zongxi 黃宗羲, Gu Yanwu 顧炎武, Zhu Yizun 朱彝尊 and Hu Wei 胡渭, but none of them undertook a systematic study of the transmitted text. For more than twenty years Yan Ruoqu analysed the old-text Shangshu and wrote his study Guwen Shangshu shuzheng 古文尚書疏證. He demonstrated that of the 58 chapters of the transmitted Shangshu a number of 25 was forged during the Jin period. For his study he compared the numbers of chapters mentioned in ancient bibliographies, the names of chapters, and then the content of each chapter, paragraphs and sentence, including historiographical statements and geographical names. His findings were a scandal because they proved that a text on which the educated elite had relied on and believed in, from the emperor down to the common teacher, was a forgery.
The most important writings of Yan Ruoqu are Shangshu guwen shuzheng 尚書古文疏證, Mao Zhu Shi shuo 毛朱詩說, Mengzi shengzu nianyue kao 孟子生卒年月考, Sishu shidi 四書釋地, Shidi yulun 釋地餘論, Sangfu yizhu 喪服翼注 and Qianqiu zaji 潛邱雜記.